Introduction:
If distal renal tubular acidosis (dRTA) is not treated appropriately, it leads to marked acid-base and electrolyte abnormalities, as well as severe bone and kidney damage. The current standard treatment for alkalinization consists of immediate-release bicarbonate and citrate salts and potassium supplementation, which require multiple daily doses, have poor overnight coverage, taste bad and cause gastrointestinal discomfort, leading to poor adherence and discontinuation of treatment. We describe the case of an adult with dRTA, who was poorly treated with standard therapy for years until the patient was switched to an innovative extended-release combination drug that has excellent efficacy and tolerability.
Methods:
A 49-year-old Caucasian woman presented to our nephrology outpatient clinic in 2010 with chronic hypokalemia, hyperchloremic metabolic acidosis, persistent alkaline urine, stage 3 chronic kidney disease, nephrocalcinosis, kidney stones, osteoporosis and short stature, suggestive of dRTA. She was dependent on frequent standard doses of oral potassium citrate and sodium bicarbonate. She suffered from gastrointestinal intolerances, such as nausea, vomiting, bloating and abdominal pain, due to the large amount of alkalizing agent released from the immediate-release formulations in the stomach. Her strength and weight decreased, and she weighed only 41 kg at 154 cm. When the health insurance company approved coverage for Sibnayal, she was switched to this new oral extended-release formulation, which consists of potassium citrate extended-release granules and potassium bicarbonate extended-release granules.
Results:
Between 2010 and February 2024, she received standard treatment with 40 mmol potassium twice daily and 500 mg sodium bicarbonate four times daily, but her serum potassium concentration fluctuated between 2.9 and 3.9 mmol/L and bicarbonate ranged between 13 and 19 mmol/L, rarely reaching 20 or 21 mmol/L. Due to the gastrointestinal side effects, 50 mg spironolactone daily was added to therapy to maintain serum potassium levels at the lower normal limit. When treatment with Sibnayal at a dose of 1 meq/kg/day was started at the end of February 2024, all previous treatment including spironolactone was discontinued. The mean plasma potassium level immediately increased from 3.6 to 5.2 mmol/L and remained between 4.5 and 5.0 mmol/L after 6 months of follow-up with Sibnayal 24 meq twice daily. No episode of hypokalemia was noted. Bicarbonate levels increased and were stable at 24 to 25 mmol/L. The renal function of our patient who was in stage 3 chronic kidney disease in 2010 and had an eGFR of 40 ml/min/1.73m2, decreased to an eGFR of 22 and is now stable at 35 mlmin/1.73m2. The new treatment was well tolerated and gastrointestinal tolerance was also good.
Conclusions:
In our case of an adult with dRTA, the combination of extended-release potassium citrate and potassium bicarbonate was shown to significantly improve metabolic acidosis and maintain potassium levels in the normal range with only two doses per day and with excellent gastrointestinal tolerability compared to standard treatments. We believe that this innovative formulation may improve compliance with long-term treatment and reduce nephrocalcinosis and nephrolithiasis as well as the consequences of hypokalemia.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.